Set 2: Muscles of trunk and arms

1. Set 2: Muscles of trunk and arms

2. Muscles of Respiration • Breathing requires the use of muscles • diaphragm • external intercostal muscles • internal intercostal muscles • Contraction of the first 2 produces Inspiration • Contraction of the last produces Forced Expiration • Normal Expiration requires little muscular activity • elastic recoil of tissues and gravity collapsing the chest • only inspiratory muscles active in braking action, so exhalation is smooth

3. Muscles of Respiration -- Diaphragm Central tendon • Muscular dome between thoracic and abdominal cavities • Muscle fascicles extend to a fibrous central tendon • Contraction flattens it • increases the vertical dimension of the thorax drawing air into the lungs • raises the abdominal pressure to help expel urine, feces and facilitating childbirth

4. Muscles of Respiration -- Intercostals • External intercostals • extend downward and anteriorly from rib to rib • pull ribcage up & outward during inspiration • Internal intercostals • extend upward and anteriorly from rib to rib • pull ribcage downward during forced expiration

5. Muscles of the Abdomen • 4 Pairs of sheetlike muscles • external oblique • internal oblique • transverse abdominis • rectus abdominis • Functions • support the viscera • stabilize the vertebral column • help in respiration, urination, defecation & childbirth

6. External oblique superficial downward anteriorly inguinal ligament Rectus abdominis vertical, straplike tendinous intersections rectus sheath linea alba Rectus Abdominis & External Oblique Rectus abdominis External oblique

7. Internal oblique anteriorly upwards Transverse abdominis horizontal fiber orientation deepest layer Internal Oblique -Transverse Abdominis Transverse abdominis Internal oblique

8. Superficial Muscles of the Back Semispinalis SpleniusLevator scapulaeRhomboideus Supraspinatus Infraspinatus Teres major Gluteus maximus Gluteus medius Trapezius Latissimus dorsi

9. Pectoralis Minor ribs 3-5 to coracoid process of scapula protracts & depresses scapula lifts ribs during forced expiration Serratus Anterior ribs 1-9 to medial border of scapula abducts & rotates or depresses scapula throwing muscle Anterior Scapular Muscle Group

10. Muscles Acting on the Scapula

11. Posterior Scapular Muscle Group • 4 Muscles • superficial = Trapezius • deep = Rhomboids & Levator scapulae • Trapezius • rotate scapula upward • retract scapula • depress scapula • With Levator scapulae & Rhomboids elevates scapula • With Serratus anterior depresses scapula

12. Rhomboideus mm. medial border of scapula to C7-T1 Levator scapulae from superior angle of scapula to C1-C4 Posterior Scapular Muscle Group

13. Muscles Acting on the Humerus • 9 Muscles cross the shoulder joint to the humerus • 2 axial muscles arise from axial skeleton • prime movers of humerus in flexion & extension • arise from sternum & clavicle OR T7-L5 & ilium Pectoralis major Latissimus dorsi

14. Muscles Acting on the Humerus • 7 scapular muscles arise from scapula • Deltoid is prime mover • flexion, extension and abduction of humerus • Coracobrachialisassists in flexion • Teres major assists in extension • Remaining 4 form the rotator cuff muscles that reinforce the shoulder joint capsule

15. Posterior View of Chest in Cadaver

16. Extending from posterior scapula to humerus supraspinatus infraspinatus teres Minor Extending from anterior scapula to humerus subscapularis Rotator Cuff Muscles Subscapularis Supraspinatus Infraspinatus Teres minor All 4 help reinforce joint capsule.

17. Anterior View of Chest in Cadaver

18. Muscles Acting on the Elbow • Principal flexors • biceps brachii • inserts on radius • brachialis • inserts on ulna • Synergistic flexor • brachioradialis • Prime extensor • triceps brachii • inserts onto ulna

19. CS Through Upper Limb & Forearm

20. Supination Supinator muscle Palm facing anteriorly Pronation Pronator teres and Pronator quadratus mm. Palm faces posteriorly Supination & Pronation of the Forearm